Effect of dietary fiber on microbial activity and microbial gas production in various regions of the gastrointestinal tract of pigs

Abstract

The microbial activity, composition of the gas phase, and gas production rates in the gastrointestinal tract of pigs fed either a lowor a high-fiber diet were investigated. Dense populations of culturable anaerobic bacteria, high ATP concentrations, and high adenylate energy charges were found for the last third of the small intestine, indicating that substantial microbial activity takes place in that portion of the gut. The highest microbial activity (highest bacterium counts, highest ATP concentration, high adenylate energy charge, and low pH) was found in the cecum and proximal colon. Greater microbial activity was found in the stomach and all segments of the hindgut in the pigs fed the high-fiber diet than in the pigs fed the low-fiber diet. Considerable amounts of 02 were found in the stomach (around 5%), while the content of 02 in gas samples taken from all other parts of the gastrointestinal tract was <1%. The highest concentrations and highest production rates for H2 were found in the last third of the small intestine. No methane could be detected in the stomach or the small intestine. The rate of production and concentration of methane in the cecum and the proximal colon were low, followed by a steady increase in the successive segments of the hindgut. A very good correlation between in vivo and in vitro measurements of methane production was found. The amount of CH4 produced by pigs fed the low-fiber diet was 1.4 liters/day per animal. Substantially larger amounts of CH4 were produced by pigs fed the high-fiber diet (12.5 liters/day). Also, the daily rate of CO2 production in the gut was higher for the pigs fed the high-fiber diet than for the pigs fed the low-fiber diet (212 versus 46 liters/day). Although the highest microbial activity was found in the cecum and proximal colon and although hydrogen production is an obligate part of anaerobic fermentation in the hindgut, only small net amounts of hydrogen were produced in these segments. Furthermore, only small amounts of methane were produced in the cecum and proximal colon. This strongly indicates that hydrogen sinks other than methane production are involved in hydrogen removal in the cecum and proximal colon of pigs. The gastrointestinal tract of pigs contains a large and diverse microbial population, with cell population densities in excess of 1010 cells per g of gut content in the large intestine, the vast

Changes in bacterial populations in the colon of pigs fed different sources of dietary fibre, and the development of swine dysentery after experimental infection

“…Determining absolute numbers of bacteria present in the colonic contents does not address the functional and metabolic activity of these cells, and clearly any interactions are very complex. Apart from changes in the number and composition of the microbiota, bacteria can also modify their metabolic pathways as a function of the substrate available (Mackie and Wilkins 1988 ;Rowland and Mallett 1988 ;Jensen and Jorgensen 1994), and through their end-products and by-products having an influence on the intestinal environment. Direct interactions between S. hyodysenteriae and the microbiota in the microenvironment of the colonic crypts are also likely to be important.…”

Assessing environmental consequences of using co-products in animal feed

“…During the digestive process, ruminants, and to a minor extent monogastric animals, emit CH4 (Steinfeld et al 2006). Changing the diet to a higher fibre composition can increase the enteric fermentation of pigs (Jensen and Jørgensen 1994). In total, however, CH4 emission from enteric fermentation of pigs is only 0.2 million ton per year compared to 2.19 for dairy cattle and 2.31 for other cattle in western Europe (Steinfeld et al 2006).…”

Difference in in vitro fermentability of four carbohydrates and two diets, using ileal and faecal inocula from unweaned piglets

“…Very little is known about the fermentative activity of the microflora from the different sites of the GIT in unweaned piglets, although a few studies have been carried out with growing pigs. 10,11 Prior to an in vivo experiment, it was decided to examine both the four fermentable ingredients chosen for the test diet and the two complete diets (control and test) for their in vitro fermentability, using both ileal digesta and faeces as inocula.…”